The present invention relates to method and apparatus for controlling weft detection on a fluid jet loom, and more particularly relates to method and apparatus for carrying out control on weft detection right after every weft exchange on a fluid jet loom equipped with a free weft exchanger which carries out weft insertion in accordance wth a given weft selection pattern.
In general on a fluid jet loom equipped with such a free exchanger, weft insertions at the first and following several picks are quite unstable and tend to cause unnecessary stoppage of the loom on detection of such unstable weft insertions.
Such troubles are caused by weft slippage due to abrupt starting of a weft reservoir in turn. The troubles are further caused by a fact that a weft long caught by a clamper, which is located upstream of a main nozzle, can hardly be delivered smoothly due to clinging to the clamper. In the case of a water jet loom, a main nozzle in rest does not initiate its ejection until right before weft exchange and no water exists in the main nozzle. As a consequence, no sufficient ejection of water is obtained as weft insertion of the first pick right after the weft exchange and such insufficient ejection tends to allow undesirable whipping of the leading end of the weft under insertion, thereby causing faulty weft insertion.
When a loom is stopped on detection of faulty weft insertion right after every weft exchange, running efficiency of the loom is lowered considerably. When the extent of a weaving defect caused by faulty weft insertion is within a tolerable limit, it is generally better to continue running of the loom in order to keep high running efficiency of the loom.